Cannot install under W2000

Running with admin privileges on a fully updated W2000
(SP4)laptop.

When trying to install, I get the following error window:

"The windows installer service could not be accessed.
This can occur if you are running in safe mode or if the
windows installer is not correctly installed. Contact
your support personnel for assistance."

(Disabled AV, etc. --> still the same problem)

I have never had any problems installing anything on this
box. If I try to install a fresh InstMsiW.exe (version
2.0) downloaded from microsoft, it says "the specified
service already exists".

Any ideas?

OK, solved it. Installed "Windows Installer 3.0
Redistributable" first:

http://www.microsoft.com/downloads/details.aspx?
FamilyID=5fbc5470-b259-4733-a914-
a956122e08e8&DisplayLang=en